PYROLYSIS PRODUCTS OF POLY(VINYL CHLORIDE), DIOCTYL PHTHALATE AND THEIR MIXTURE

The pyrolysis of PVC, dioctyl phthalate (DOP) and their mixture has be en conducted in air and inert atmosphere and the products studied usin g thermal volatilisation analysis (TVA) and subambient thermal volatil isation analysis. Gas, liquid and tar fractions were separated and ana lysed by CC-MS and FTIR. A large number of aromatic and alkyl aromatic compounds were found in the PVC liquid and tar fractions, confirming the results previously reported in the literature. Pyrolysis in the pr esence of air does not change the nature of the products, though the r elative amounts may be different. Oxygen-containing volatiles are not formed. The oxygen-containing groups are formed in the polymer and pas s into the tar as large fragments split from the crosslinked network. Among DOP pyrolysis products benzene, toluene, benzaldehyde, phthalic acid, phthalic anhydride, isoalkene, unsaturated ketones and alcohols are the most important. The pyrolysis of the PVC-DOP mixture produces, beside the products of the pure components, new products originating in the reactions of the free radicals formed in the individual compone nts. PVC-DOP mixture exhibits retarded dehydrochlorination during the TVA experiment. This behaviour is similar to that previously observed in this laboratory for PVC-poly(tetramethylene sebacate) blends and su pports the idea of reaction between chain carriers in PVC dehydrochlor ination and the methylene groups of esters.